Pitavastatin is a cholesterol lowering agent of the class of HMG-CoA reductase inhibitor. The HMG-CoA reductase enzyme catalyzes the conversions of HMG-CoA to mevalonate. Inhibitors of HMG-CoA reductase are commonly referred to as “statins.” Statins are therapeutically effective drugs used for reducing low density lipoprotein (LDL) particle concentration in the blood stream of patients at risk for cardiovascular disease.
Pitavastatin is one of the synthetic statins which is chemically known as (3R, 5S, 6E)-7-[2-cyclopropyl-4-(4-fluorophenyl) quinoline-3-yl]-3,5-dihydroxy-6-heptenoic acid represented by structural formula (1):

Pitavastatin and its pharmaceutically acceptable salts are described in U.S. Pat. No. 5,753,675 patent and U.S. Pat. No. 5,856,336 patent, respectively.
Processes for the preparation of Pitavastatin are well documented in the literature. European patents, EP 0304063 and EP 1099694 and reports by Miyachi et al (Tetrahedron Letters (1993) vol. 34, pages 8267-8270) and Takahashi et al (Bull. Chem. Soc. Japan (1995) Vol. 68, 2649-2656) describe processes for preparation of Pitavastatin.
U.S. Pat. No. 5,872,130 patent discloses sodium salt of Pitavastatin. This patent, however, is silent about the solid state form of Pitavastatin Sodium.
It is generally known in the art that active pharmaceutical ingredients frequently do not exhibit the range of physical properties that makes them directly suitable for development. One of the approaches that is used to modify the characteristics of drug substances is to employ a salt form of the substance, since salts enable one to modify aqueous solubility, dissolution rate, solution pH, crystal form, hygroscopicity, chemical stability, melting point and even mechanical properties. The beneficial aspects of using salt forms of active pharmaceutical ingredients are well known and represent one of the means to increase the degree of solubility of otherwise intractable substances and to increase bioavailability.
Although the known salts of Pitavastatin like sodium, potassium, magnesium, calcium etc. and their polymorphic forms may address some of the deficiencies in terms of formulated product and its manufacturability. There remains a need for yet further improvement in these properties as well as improvements in other properties such as flowability, and solubility.
Polymorphism is a known phenomenon among pharmaceutical substances. It is commonly defined as the ability of any substance to exist in two or more crystalline phases that have a different arrangement and/or conformation of the molecules in the crystal lattice. Different polymorphic forms of the same pharmaceutically active moiety also differ in their physical properties such as melting point, solubility, chemical reactivity, etc. These properties may also appreciably influence pharmaceutical properties such as dissolution rate and bioavailability.
Further, the discovery of new polymorphic forms and solvates of an active pharmaceutical ingredient provides broader scope to a formulation scientist for formulation optimization, for example by providing a product with different properties, e.g., better processing or handling characteristics, improved dissolution profile, or improved shelf-life. For at least these reasons, there is a need for polymorphs of Pitavastatin salts such as Pitavastatin sodium.
New polymorphic forms and hydrates and/or solvates of a pharmaceutically acceptable salt of Pitavastatin can also provide an opportunity to improve the performance characteristics of a pharmaceutical product.
Therefore, there is a scope to prepare novel polymorphic forms of Pitavastatin sodium and hydrates and/or solvates.